In the printing and decorating art where ink is applied to a recipient surface by a printing plate of a high speed apparatus, the ink so applied must be of a consistency and uniformity on the printing plate so that precision transfer of the ink from the plate to the recipient surface can occur. In the can decorating art, for example, ink which originates from an ink fountain means is transferred through a series of roll assemblies before reaching a blanket segment for final application to the can surface. The various roll assemblies, which generally include at least one vibrator roll assembly, act to prepare the physical characteristics required of the ink to achieve its satisfactory application in the decoration of the can surface. The can decorating apparatus taught, for example in copending and commonly-assigned U.S. patent application Ser. No. 916,604, filed Oct. 8, 1986, and incorporated herein by reference, describes a series of roll assemblies employed in ink supply and transfer.
Because the ink must be uniformly spread when it reaches the printing plate for ultimate application to the decorated surface, vibrator roll assemblies are used. In such an assembly, the vibrator roll must not only rotate, but also oscillate simultaneously to thereby effectuate a smooth and uniform ink distribution. Usual ratios of shaft revolution per oscillation generally range from about 5:1 to 30:1.